JP6004872B2 - Moving bed filtration tank and septic tank - Google Patents

Description

  The present invention relates to a moving bed type filtration tank and a purification tank provided with a filter medium and an air lift pump for transferring the filter medium from the tank bottom to the tank upper part.

  As a conventional moving bed type filtration tank, for example, a moving bed type filtration tank shown in Patent Document 1 is known. Here, the filter medium filled in the tank captures (filters) suspended solids (sludge) contained in the water to be treated, and air is directly supplied to the pumping channel from the air blowing portion provided on the lower side surface of the water channel wall. The air lift pump is operated by blowing, and the filter medium is sucked into the pumping channel from the bottom of the tank and recirculated to the upper part of the tank, so that suspended substances attached to the filter medium are separated and discharged out of the tank.

JP 2003-53110 A

However, in the conventional moving bed type filtration tank, there are cases where a plurality of filter media gathered at the bottom of the tank form a bridge in the horizontal direction near the suction port of the pumping path, thereby blocking the pumping path. .
An object of the present invention is to provide a moving bed type filtration tank and a septic tank in which the pumping path is not easily blocked by the bridge formation of the filter medium.

1st characteristic structure which concerns on the septic tank of this invention is a septic tank provided with the moving bed type | formula filtration tank which has a filter medium and the air lift pump which transfers the said filter medium from a tank bottom part to a tank upper part, In the said air lift pump, the said filter medium moves A water passage wall forming a possible pumping channel, a filter medium inlet, a filter medium discharge port, and an air supply means for supplying air to the pumping channel, and a ridge is provided above the outer periphery side of the filter medium inlet An upper surface of the ridge is inclined downward in a direction away from the filter medium inlet, and a lower surface of the ridge is inclined upward in a direction away from the filter medium inlet, and the lower surface of the ridge and the tank bottom Is formed between the minimum distance Smin between the lower end of the upper surface of the trough and the tank bottom, and the maximum distance Tmax between the filter medium inlet and the tank bottom Smin / Tmax. <In the point of having a relationship is there.

[Action and effect]
According to this configuration, since the soot is provided above the outer peripheral side of the filter medium inlet, the filter medium descending from the top of the tank is retained above the soot, and gradually from the lower end of the soot toward the surface of the bottom of the tank. It can be moved by settling. Further, at the portion of the minimum distance Smin between the lower end of the basket and the tank bottom, the amount of the filter medium moving toward the filter medium inlet is limited, and the maximum distance Tmax between the filter medium inlet and the tank bottom is set. By setting so as to satisfy Smin / Tmax <1, a wider space is formed in the space of the minimum distance Smin portion. As a result, the packing density of the filter medium gathering in the vicinity of the filter medium inflow port decreases, and bridge formation by the filter medium is less likely to occur, so that the pumping path can be prevented from being blocked.
Moreover, according to this structure, the filter medium descend | falling from the tank upper part can be made to stay on the upper surface of a tub, and can be gradually settled and moved toward the tank inner surface side along the inclined upper surface of the tub. Further, when the filter medium that has passed between the lower end of the tank and the inner surface of the tank is moved toward the filter medium inlet along the surface of the tank bottom, the filter medium is inclined upward in the direction away from the filter medium inlet on the lower surface of the tank. The inclined surface serves as a guide plate, and the flow of the filter medium can be adjusted to guide the filter medium more smoothly to the filter medium inlet .

  According to a second characteristic configuration, the basket has a hanging wall portion, and the vertical length of the hanging wall portion is equal to or greater than the maximum width of the filter medium, and is between the lower end of the hanging wall portion and the tank bottom portion. Is the point that is the minimum distance Smin.

[Action and effect]
According to this structure, it can guide to a filter medium inflow port in an order from a filter medium which settles in a hanging wall part among filter media which stays above a bowl. Moreover, when the vertical length of the vertical wall portion is equal to or greater than the maximum width of the filter medium, when the filter medium passes between the lower end of the vertical wall section that wraps around from the top of the trough and the bottom of the tank, the entire filter medium Since there is little possibility that the said filter medium touches the surface of a tank bottom until it passes through a drooping wall part, a movement amount can be restrict | limited, making the movement of a filter medium smooth at the lower end of a drooping wall part.

  The third characteristic configuration is that the maximum distance Tmax is equal to or greater than a distance obtained by adding the minimum distance Smin and the maximum width of the filter medium.

[Action and effect]
According to this configuration, the space formed by providing a difference between the distance between the lower end of the basket and the bottom of the tank and the distance between the filter medium inlet and the tank bottom forms at least the maximum width of the filter medium. Therefore, the packing density of the filter medium gathering in the vicinity of the filter medium inflow port is further reduced, and bridge formation by the filter medium is difficult to occur, so that the pumping path can be more reliably prevented from being blocked.

  The fourth characteristic configuration is that Smin / Tmax <0.85.

[Action and effect]
According to this structure, the space which arises by providing a difference in the distance between the lower end of a basket and a tank bottom part, and the distance between a filter medium inflow port and a tank bottom part becomes easier to be formed. As a result, the packing density of the filter medium gathering in the vicinity of the filter medium inflow port is reduced, and bridge formation by the filter medium is less likely to occur, so that the pumping path can be more reliably prevented.

The fifth characteristic configuration is that the dredger is fixed to the water channel wall, and the water channel wall is provided with a communication portion that leads from the inner space of the dredger to the pumping channel.

[Action and effect]
According to this configuration, since the trough is provided on the water channel wall, the filter medium is more smoothly moved from the upper side to the lower end of the trough without causing disturbance of the filter medium due to the turbulent flow from the gap generated between the water channel wall and the trough. Can be moved to. In addition, by providing a communication portion that communicates the inner space of the kite with the pumping channel on the channel channel, air inside the kite can be guided to the pumping channel, and loss of supplied air can be suppressed.

A sixth characteristic configuration is that an air blowing portion of the air supply means is provided at the tank bottom.

[Action and effect]
According to this configuration, since the air blowing portion is provided at the bottom of the tank, the filter medium gathered at the bottom of the tank is reliably transferred to the pumping path by the upward flow of the water to be treated generated by the air supplied from the air blowing portion. Since it is inhaled, it is difficult to stay at the bottom of the tank.

It is a top view which shows the inside of a septic tank. It is a side view which shows the inside of a septic tank. It is the III-III arrow directional view of FIG. It is the IV-IV line arrow directional view of FIG. It is the VV arrow directional view of FIG. It is a perspective view which shows the inside of a support | carrier fluidization tank and a moving bed type filtration tank, Comprising: (a) shows the state which accommodated the filter medium in the moving bed type filtration tank, (b) is the inside of a moving bed type filtration tank. Shows a state where the filter medium is omitted for easy understanding. It is a side view which shows the inside of a moving bed type filtration tank. It is the side view to which a part inside moving bed type filtration tank was expanded. It is a perspective view which shows a transfer amount restriction | limiting part. It is the schematic which shows another form (a)-(d) of a filter medium inflow port. It is the schematic which shows another form of a filter medium inflow port. It is the schematic which shows another form of a filter medium inflow port. It is the schematic which shows another form of a ridge. It is the schematic which shows another form of a ridge. It is the schematic which shows another form of a ridge. It is the schematic which shows another form of a filter medium inflow port.

Embodiments of the present invention will be described below with reference to the drawings.
Embodiment
1 to 5 show a septic tank that purifies domestic wastewater (sewage) as treated water.
As shown in FIGS. 1 and 2, the inside of the septic tank is a biological treatment tank A for biologically treating the treated water, and a moving bed type filtration for filtering the treated water treated in the biological treatment tank A with the filter medium 23. Tank B (an example of a water treatment device), treated water tank C for temporarily storing the treated water filtered in the moving bed type filtration tank B, and disinfection tank D for disinfecting the treated water stored in the treated water tank C It is divided into.

  The biological treatment tank A is divided into a primary treatment tank A1 that receives an treated water (raw water) flowing from the outside and anaerobically treats it, and a carrier fluidized tank A2 as an aerobic treatment tank that aerobically treats the treated water. ing. The primary treatment tank A1 is divided into a precipitation separation tank E1 and an anaerobic filter bed tank E2.

  The treated water (raw water) from the outside flows into the sedimentation separation tank E1 from the inflow part 1, and the treated water sterilized in the disinfection tank D is discharged from the discharge part 2 to the outside.

  The sedimentation separation tank E1 and the anaerobic filter bed tank E2 are divided forward and backward by the first horizontal partition wall 4, and the anaerobic filter bed tank E2, the carrier flow tank A2 and the moving bed type filtration tank B are front and rear by the second horizontal partition wall 5. It is divided into.

  The carrier fluidized tank A2, the moving bed type filtration tank B and the treated water tank C are partitioned on the left and right by the vertical partition wall 7, and the moving bed type filtration tank B and the treated water tank C are partitioned on the front and rear by the partition wall 8, D is defined in the upper part on the inner side of the carrier flow tank A2.

  As shown in FIGS. 3 and 4, the first horizontal partition 4 is provided with a first advection port 11 for advancing water to be treated from the precipitation separation tank E1 to the anaerobic filter bed tank E2. The advection tube 17 and the advection tube 19 are attached.

  As shown in FIG. 5, the second horizontal partition wall 5 is provided with a second advection port 12 for advancing water to be treated from the anaerobic filter bed tank E2 to the carrier flow tank A2.

  As shown in FIG. 6, a third advection port 13 through which the water to be treated flows from the carrier fluid tank A2 to the moving bed type filtration tank B is provided in the partition wall portion of the vertical partition wall 7 near the water surface. It is provided over a position higher than the water surface WL and a lower position.

At the lower end portion of the partition wall 8 between the moving bed type filtration tank B and the treated water tank C, a fourth advection port 14 for moving the treated water from the moving bed type filtration tank B to the treated water tank C is provided.
The third advection port 13 and the fourth advection port 14 are formed with a large number of slit holes so that the fluid carrier 21 and the filter medium 23 accommodated in the carrier fluid tank A2 and the movable bed type filtration tank B do not flow out.
The precipitation separation tank E1 and the anaerobic filter bed tank E2 may have a function as a flow rate adjusting unit that temporarily stores water to be treated at the peak inflow in a time zone such as morning and evening.

  Therefore, the water to be treated which has flowed in from the inflow portion 1 is transferred to the precipitation separation tank E1, the anaerobic filter bed tank E2, the carrier fluidized tank A2, the moving bed type filtration tank B, the treated water tank C, and the disinfection tank D in this order and discharged. It is discharged from the part 2 to the outside.

  The to-be-treated water that has flowed in from the inflow portion 1 is precipitated and separated in the precipitation separation tank E1, guided to the advection pipe 17 and rises along the first horizontal partition 4 and is provided in the first horizontal partition 4. It flows into the anaerobic filter bed tank E2 from one advection port 11. The anaerobic filter bed tank E2 includes an anaerobic filter bed 18 that holds anaerobic microorganisms.

  The water to be treated which has flowed into the anaerobic filter bed tank E2 from the first advection port 11 is guided by the advection pipe 19 and descends along the first horizontal partition wall 4 and passes through the anaerobic filter bed 18 upward to be anaerobically treated. In addition, the water to be treated, in which suspended solids are trapped and solid matter is almost decomposed, is guided to the advection baffle 20 and flows into the upper part of the carrier flow tank A2 from the second advection port 12 provided in the second horizontal partition wall 5. To do.

  As shown in FIG. 6, a large number of fluid carriers 21 carrying aerobic microorganisms are accommodated in the carrier fluid tank A2 so that they can flow together with the water to be treated, and an aeration diffuser 22 is provided at the bottom of the tank. Is provided.

  The water to be treated that has flowed into the carrier fluid tank A2 is aerobically treated with the fluid carrier 21 while being supplied with oxygen by supplying air bubbles from the air diffuser 22, and then, along with the suspended solids (sludge), the vertical partition walls. 7 constantly flows into the moving bed type filtration tank B from the third advection port 13 provided in 7 and the suspended matter (sludge) in the carrier flow tank A2 decreases.

  As shown in FIGS. 6 and 7, the lower part of the moving bed type filtration tank B is filled with a large number of substantially spherical filter media 23 having a specific gravity greater than that of water so as to be submerged and accumulated. Yes.

  As shown in FIG. 7, the moving bed type filtration tank B includes a filter medium 23 and an air lift pump P. The air lift pump P includes a water channel wall 26 that forms a pumping channel 25 in which treated water and the filter medium 23 can move, a filter medium inlet 32 at the lower end of the pump channel 25, and a filter medium discharge port 28 at the upper part of the pump channel 25. And an air supply means for supplying air to the pumping path 25. The air lift pump P sucks the water to be treated and the filter medium 23 from the deepest part 50 into the pumping path 25 and transfers it to the upper part of the tank, and repeatedly circulates this to constantly wash the filter medium 23.

  The water channel wall 26 is fixed along the vertical direction at the corner where the second horizontal partition wall 5 and the vertical partition wall 7 intersect (see FIG. 1), and the filter medium discharge port 28 is covered in the moving bed type filtration tank B. It is provided so as to be higher than the liquid level WL of the treated water. By providing the water channel wall 26 at the corner, it is possible to limit the direction in which the water to be treated and the filter medium 23 flow in, and the risk of turbulence is reduced.

  The pumping path 25 is formed inside the channel wall 26, and its cross-sectional shape has a uniform shape over the entire longitudinal direction. In the present embodiment, the filter medium discharge port 28 is provided at the upper end of the pumping path 25, but the present invention is not limited to this configuration, and the filter medium discharge port 28 is provided at any position as long as it is higher than the surface of the water to be treated. Also good.

  As shown in FIG. 8, the bottom of the moving bed type filtration tank B is extended to the deepest part 50 disposed immediately below the pumping path 25 and from the deepest part 50 to the lower end of the tank inner face 36 obliquely above. It has two flat tank side bottom surfaces 31 and is formed in a downward truncated pyramid shape (see FIG. 6A).

  In the present embodiment, the tank-side bottom surface 31 is formed as a flat inclined surface, but is not limited to this, and may be combined with an arcuate surface, formed into a conical surface, or inclined. You may comprise on a flat surface without doing.

  Above the outer peripheral side of the filter medium inlet 32, there are two flat upper surfaces 29 inclined downward in a direction away from the filter medium inlet 32, and a lower surface 45 inclined in an upward gradient in a direction away from the filter medium inlet 32. A bag 30 is provided. The trough 30 in the present embodiment is fixed to the water channel wall 26.

  A hanging wall portion 34 extending vertically downward from the lower end of the upper surface 29 is provided at the end portion of the collar 30. It is desirable that the vertical length of the hanging wall 34 is set to be equal to or greater than the maximum width of the filter medium 23. In the present embodiment, the distance between the lower end of the vertical wall portion 34 and the tank side bottom surface 31 is the minimum distance Smin between the lower end of the basket 30 and the tank bottom portion. Further, the distance between the filter medium inlet 32 and the deepest part 50 is the maximum distance Tmax between the filter medium inlet 32 and the tank bottom. The minimum distance Smin and the maximum distance Tmax have a relationship of Smin / Tmax <1. The minimum distance Smin between the lower end of the rod 30 and the bottom of the tank is the maximum distance Tmax, whether it is a distance from the lower end of the hanging wall 34 to the bottom of the tank in the vertical direction or a vertical distance to the bottom of the tank. Any method may be used as long as it is the same as the measurement method.

  In the moving bed type filtration tank B in the present embodiment, since the horizontal cross-sectional area of the inner wall of the moving bed type filtration tank B becomes narrower as it goes downward along the upper surface 29, the filter medium 23 that settles in the tank has an upper surface. It stays in the upper part of 29, forms a staying part, and gradually moves along the upper surface 29 toward the tank inner surface 36 side. The staying part of the filter medium 23 on the upper surface 29 forms a filtration layer for filtering the water to be treated.

  The filter medium 23 in the staying part further sinks, passes between the lower end of the hanging wall part 34 and the tank side bottom face 31, moves to the deepest part 50 side along the tank side bottom face 31, and enters the filter medium inlet. 32 is sucked into the pumping path 25 together with the water to be treated.

  In addition, at the portion of the minimum distance Smin between the lower end of the trough 30 and the tank bottom, the amount of the filter medium 23 moving toward the filter medium inlet 32 is limited, and between the filter medium inlet 32 and the tank bottom. Is set so that Smin / Tmax <1 is satisfied, a wider space W is formed in the space of the minimum distance Smin portion. As a result, the packing density of the filter medium 23 gathered in the vicinity of the filter medium inlet 32 is lowered, and it is difficult for bridge formation by the filter medium 23 to occur, so that the pumping path 25 can be prevented from being blocked.

  Moreover, in order to form the space W according to the difference between the distance between the lower end of the basket 30 and the tank bottom and the distance between the filter medium inlet 32 and the tank bottom, the maximum distance Tmax is the minimum distance. The distance is preferably equal to or greater than the sum of Smin and the maximum width of the filter medium 23, and more preferably, the minimum distance Smin / the maximum distance Tmax <0.85.

  The air supply means includes an air supply pipe 27 connected to an air compressor or the like (not shown), and an air blowing portion 27a that blows out air from the air supply pipe 27. In the present embodiment, the air blowing part 27 a is provided in the deepest part 50. That is, the air blowing part 27 a is provided directly below the filter medium inlet 32 of the pumping path 25, and is configured to blow air from below the filter medium 23 gathered at the deepest part 50. As shown in FIG. 7, the air supply pipe 27 is disposed along the treated water tank C side of the partition wall 8.

  According to the said structure, the filter medium flow of the pumping-up path 25 by the upward flow of the to-be-processed water produced by the air supplied to the deepest part 50 of the moving bed type filtration tank B and the sedimentation sludge from the air blowing part 27a is carried out. Compared to the conventional case in which the air supply pipe 27 is connected to the lower side surface of the water channel wall 26, the filter medium 23 and sludge can be easily prevented from staying in the deepest part 50.

  Further, the lower surface 45 of the eaves 30 extends obliquely upward from the lower end of the water channel wall 26 (the upper end of the filter medium inlet 32) toward the lower end of the upper surface 29. According to this configuration, the filter medium 23 that has passed between the lower end of the hanging wall portion 34 and the tank-side bottom surface 31 is guided toward the lower side of the filter medium inlet 32 by the lower surface 45 of the tank 30 and the tank-side bottom surface 31. Therefore, the movement of the filter medium 23 becomes smooth, and the filter medium 23 can be prevented from staying at the bottom of the tank.

  In the present embodiment, an opening 46 through which air can pass while preventing passage of the filter medium 23 is provided on the lower surface 45 of the bowl 30. The opening 46 is a through hole that communicates with the space inside the flange 30, and is formed in the upper end portion of the lower surface 45. The inner diameter of the opening 46 is set so that the air supplied from the air blowing part 27a and the water to be treated are allowed to pass but the filter medium 23 is not allowed to pass.

  Further, a communication portion 47 is formed on the wall surface of the water channel wall 26 near the upper end portion of the eaves 30. The communication part 47 is a through hole that communicates with the pumping path 25 from the space inside the raft 30, and the inner diameter of the communication part 47 allows the air and the water to be treated supplied from the air blowing part 27a to pass therethrough. The filter medium 23 that moves 25 is set not to pass through.

  Of the air supplied from the air blowing portion 27 a, the air that has not entered the filter medium inlet 32 of the pumping channel 25 is guided along the lower surface 45 and flows into the space inside the eaves 30 from the opening 46. To do. And the inflowed air is guided along the back surface of the upper surface 29 of the eaves 30, passes through the communication portion 47, and merges with the pumping path 25.

  According to the above configuration, the filter layer formed by the plurality of filter media 23 staying on the upper surface 29 is not disturbed by the air that has not entered the filter media inlet 32 of the pumping path 25. Furthermore, since the air that has not entered the filter medium inlet 32 of the pumping path 25 can be merged with the pumping path 25, the loss of air supplied to operate the air lift pump P can be minimized. .

  As shown in FIG. 9, on the filter medium discharge port 28 side of the pumping channel 25, a part of the water to be treated discharged from the filter medium discharge port 28 together with suspended solids (sludge) is stored in a tank other than the carrier flow tank A2. Moreover, the transfer part 37 which always transfers to tanks other than the moving bed type filtration tank B is provided.

The air lift pump P and the transfer unit 37 constitute the water to be treated circulating means F, and the air lift in which the water to be treated that has passed through the moving bed type filtration tank B after being treated in the carrier flow tank A2 is disposed in the moving bed type filtration tank B. It transfers to the precipitation separation tank E1 through the pump P and the transfer part 37.
By transferring and circulating the water to be treated from the carrier flow tank A2 to the primary treatment tank A1, the nitrification and denitrification treatment of the water to be treated is promoted.

  As shown in FIG. 9, the transfer unit 37 has a sediment separation tank E1 disposed on the upstream side of the carrier fluidized tank A2 in the treatment tank disposed in the biological treatment tank A for a part of the water to be treated. Is provided with a transfer rod for transfer (return).

  The transfer trough (transfer section) 37 is disposed so that the transfer start end faces the vicinity of the filter medium discharge port 28 of the pumping path 25, is supported by the second horizontal partition wall 5, and is treated water discharged from the filter medium discharge port 28. A part of the water is introduced and transferred to the precipitation separation tank E1.

  The transfer start part of the transfer tank 37 is provided with a transfer amount limiting unit 38 that limits the transfer amount of the water to be treated that can be transferred to the precipitation separation tank E1. The transfer amount limiting unit 38 is configured by providing a weir plate that allows the water to be treated to pass along with the sludge and that is formed with a large number of slit holes 38 a arranged in the slit width direction to prevent the filter medium 23 from passing therethrough. .

  The weir plate (transfer amount limiting portion) 38 is supported at the transfer start side end of the transfer rod 37 by the guide frame 39 provided on the second horizontal partition wall 5 so as to be slidable in the vertical direction. Thus, the transfer amount of the water to be treated to the precipitation separation tank E1 can be adjusted.

  As shown in FIG. 6, water to be treated can be circulated between the carrier fluidized tank A2 and the movable bed type filtration tank B in the vertical partition wall 7 that divides the carrier fluidized tank A2 and the movable bed type filtration tank B. A circulation path 40 is provided. The circulation path 40 has a third advection port 13 as an upper advection port formed in the vertical partition wall 7 and a lower advection port formed in a partition wall portion at a position lower than the third advection port 13 in the vertical partition wall 7. 5 advection ports 41 are provided. The fifth advection port 41 is configured by providing a large number of slit holes that prevent the passage of the filter medium 23.

  In the circulation path 40, the water to be treated in the moving bed type filtration tank B flows into the carrier flow tank A2 from the fifth transfer port 41, and the water to be treated in the carrier flow tank A2 flows from the third flow port 13 into the moving bed type filtration tank. The treated water is circulated in a state of flowing into B.

  The fifth advection port 41 is formed so as to face the staying part of the filter medium 23 in the moving bed type filtration tank B, and the third advection port 13 and the fifth advection port 41 are used for aeration of the carrier fluidized tank A2. It is formed in the partition part facing the diffuser 22 by shifting the position in the vertical direction.

  The treated water filtered in the moving bed type filtration tank B is transferred to the treated water tank C through the fourth transfer port 14 formed in the partition wall 8 and temporarily stored, and then transferred to the disinfection tank D and disinfected. And released to the outside.

[Other Embodiments]
The outer peripheral shape of the filter medium inlet 32 in the above-described embodiment is not limited to a shape that opens flat on the deepest portion 50 side as shown in FIG. 8, and the lower end of the water channel wall 26 is a tank. The distance between the bottom and the bottom portion changes, and the maximum distance Tmax (see FIG. 12) and the minimum distance Tmin (see FIG. 12) have a relationship of 0 ≦ Tmin / Tmax <1.0. You may comprise as follows. For example, as shown in FIG. 10, the distance between the lower end of the water channel wall 26 and the tank bottom is continuous from the part H related to the maximum distance Tmax at the lower end of the water channel wall 26 toward the part L related to the minimum distance Tmin. It is good also as shapes, such as (a) step shape (b) step shape (c) circular arc shape (d) taper shape etc. which reduce automatically or intermittently. With this configuration, it is possible to further limit the inflow direction of the water to be treated and the filter medium 23 flowing into the water channel wall 26 provided at the corner where the second horizontal partition wall 5 and the vertical partition wall 7 intersect. It is possible to suppress the generation of turbulence more reliably. The minimum distance Tmin is preferably less than 100 mm, and more preferably 0 to 70 mm. The maximum distance Tmax is desirably 100 to 300 mm. Further, Tmin / Tmax is more preferably 0 ≦ Tmin / Tmax ≦ 0.7, and further preferably 0 ≦ Tmin / Tmax ≦ 0.5. In the above-described embodiment, the case where the minimum distance Tmin = 0 is illustrated, but more desirably, the minimum distance Tmin> 0 may be used as shown in FIGS. 11 and 12, and in this case, Tmax / Tmin ≦ 3. It is desirable that Moreover, as shown in FIG. 11, the filter medium inlet 32 may be formed by notching the lower end portion of the pumping channel 25 obliquely so as to open to the second horizontal partition wall 5 side. 0.3 ≦ Tmin / Tmax ≦ 0.5 is desirable.

  In the above-described embodiment, the lower surface 45 of the eaves 30 extends obliquely upward from the lower end of the water channel wall 26, but is not limited thereto, and may be configured to extend from the water channel wall 26 in the horizontal direction.

  In the above-described embodiment, the upper surface 29 of the eaves 30 is formed by two flat inclined plates surrounding the water channel wall 26. However, the present invention is not limited to this, and the channel wall is formed by three or more plates. It may be formed so as to surround 26 or may be conical.

  As shown in FIGS. 11 to 15, the bag 30 in the above-described embodiment does not necessarily include the lower surface 45. As shown in FIG. 13, the trough 30 may not be fixed to the water channel wall 26 but may be fixed to the surrounding second horizontal partition wall 5 or the vertical partition wall 7 (see FIG. 1). Or holes 52 may be provided.

  As shown in FIG. 14, the hanging wall 34 may be provided inside the upper surface 29 instead of the lower end of the upper surface 29.

  As shown in FIG. 15, the vertical wall portion 34 may not be provided, and the filter medium 23 that has passed between the lower end of the upper surface 29 and the tank-side bottom surface 31 may be sucked from the filter medium inlet 32.

  The shape of the filter medium 23 is not limited to a spherical shape, and may be a polygonal shape. Moreover, when using the spherical filter medium 23, it is desirable that the diameter shall be 10-30 mm.

  As shown in FIG. 16, the filter medium inlet 32 may be provided on the side surface of the water channel wall 26.

  The water treatment apparatus according to the present invention can be applied not only to a moving bed type filtration tank in a septic tank but also to a filtration tank used in a sewage treatment plant.

23 Filler (filter material)
25 Pumping channel 26 Water channel wall 27 Air supply pipe (air supply means)
27a Air blowing part (air supply means)
28 Filter media outlet (filler outlet)
29 Upper surface 30 庇 31 Tank side bottom (tank bottom)
32 Filter media inlet (filler inlet)
34 hanging wall 45 lower surface 50 deepest part (tank bottom)
P Air lift pump

Claims (6)

In a septic tank comprising a moving bed type filtration tank having a filter medium and an air lift pump for transferring the filter medium from the tank bottom to the tank upper part,
The air lift pump has a water channel wall that forms a pumping path through which the filter medium can move, a filter medium inlet, a filter medium discharge port, and an air supply means for supplying air to the pumping path, and the filter medium inlet A ridge is provided on the outer periphery side of the
The upper surface of the ridge is inclined downward in a direction away from the filter medium inlet, and the lower surface of the ridge is inclined upward in a direction away from the filter medium inlet, between the lower surface of the basket and the bottom of the tank. A waterway is formed in
The septic tank in which the minimum distance Smin between the lower end of the upper surface of the basket and the tank bottom and the maximum distance Tmax between the filter medium inlet and the tank bottom have a relationship of Smin / Tmax <1. The vertical wall has a vertical wall part, and the vertical length of the vertical wall part is not less than the maximum width of the filter medium, and the distance between the lower end of the vertical wall part and the tank bottom is the minimum distance. The septic tank according to claim 1, which is Smin. The septic tank according to claim 1 or 2, wherein the maximum distance Tmax is not less than a distance obtained by adding the minimum distance Smin and the maximum width of the filter medium. The septic tank according to any one of claims 1 to 3, wherein the Smin / Tmax <0.85. The septic tank according to any one of claims 1 to 4 , wherein the dredger is fixed to the water channel wall, and the water channel wall is provided with a communication portion that leads from the inner space of the dredger to the pumping channel. The septic tank according to any one of claims 1 to 5 , wherein an air blowing section of the air supply means is provided at the tank bottom.

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